1. Field of the Invention
The present invention relates to a viscous fluid coupling device that can be used for cooling fan controllers of internal combustion engines.
2. Description of the Related Art
As a related art of such a viscous fluid coupling device, there is provided a coupling device having following configuration. That is, a conventional viscous fluid coupling device includes: a housing; a partition that divides the housing into a reservoir chamber and an operation chamber; communication holes that are provided in the partition and make the reservoir chamber and the operation chamber to communicate with each other; a rotator that is disposed inside the operation chamber and fixed to one end of a drive shaft and integrally rotates with the drive shaft; a valve that is disposed in the reservoir chamber and opens and closes the communication hole; a rod that is fixed at one end to the valve and fixed at the other end to the inner circumferential side of a vortical bimetal and rotatably supported on the housing; an attaching outer end formed by bending the outer circumferential side of the bimetal outer-circumferentially; and a bimetal holder that fixes the attaching outer end, wherein a T-shaped support is fixed by press-fitting or caulking to the opposite side of the attaching outer end fixing side and the housing; a damper rubber is retained on the inner side of the support by an adhesive, baking adhesion, or the like, and the other surface of the damper rubber is set to be in contact with or maintain a slight distance from the outer circumference of the bimetal (for example, refer to U.S. Pat. No. 4,998,607).
However, in the conventional viscous fluid coupling device, a support is required for reducing vibrations, so that press-fitting or caulking must be carried out. This results in an increase in the number of parts and an increase in the number of assembling steps. Furthermore, vibrations in the rod axial direction of the bimetal caused by vehicle vibrations cannot be reduced.
There is a conventional viscous fluid coupling device provided with a plate to be attached with a rubber vibration isolator for preventing bimetal vibrations is also available (for example, refer to JP-UM-A-54-056069).
However, in the conventional viscous fluid coupling device, the rubber vibration isolator comes into contact with the plate from the outer circumferential direction of the bimetal, and is disposed at the outside of the bimetal. This results in an increase in the number of parts and an increase in assembling steps. In addition, vibrations in the rod axial direction of the bimetal cannot be reduced. Furthermore, a plurality of thinning holes are provided for more contacting the bimetal with the outside temperature, however, only forming these holes cannot prevent the air flow passing through a radiator from being limited, and the bimetal sensitivity lowers, and the bimetal may not normally operate.
On the other hand, the viscous fluid coupling device is disposed at the rear side of a radiator and the bimetal detects the air temperature at the rear side of the radiator and controls the viscous fluid coupling device, however, when the viscous fluid coupling device operates and the temperature of the viscous fluid coupling device rises, due to heat release from the housing of the viscous fluid coupling device, the bimetal may malfunction.